Re: [BUG] irqchip: armada-370-xp: workqueue lockup

[Marc Zyngier <maz@kernel.org>]

On Wed, 22 Sep 2021 07:49:05 +0100,
Steffen Trumtrar <s.trumtrar@pengutronix.de> wrote:
> 
> 
> Hi,
> 
> Marc Zyngier <maz@kernel.org> writes:
> > It isn't obvious to me how reverting this patch fixes anything.  The
> > fasteoi flow does the same thing as far as the IPI driver is concerned
> >
> 
> didn't the fasteoi flow just call the irq_eoi earlier? Same as the
> irq_ack now?

Yes, of course, you are correct. Another proof that the whole initial
fasteoi flow that used EOI as an ACK was *a bad idea* (tm).

> 
> >
> > However, it appears that I have broken that part much earlier in
> > f02147dd02eb ("irqchip/armada-370-xp: Configure IPIs as standard
> > interrupts"), as the write to ARMADA_370_XP_IN_DRBEL_CAUSE_OFFS that
> > used to occur before the handling (an ACK) has now been moved after as
> > an EOI. That's a pretty good way to lose edge interrupts.
> >
> > Could you try the following patch on top of 5.12-rc2?
> >
> > Thanks,
> >
> > 	M.
> >
> > diff --git a/drivers/irqchip/irq-armada-370-xp.c b/drivers/irqchip/irq-armada-370-xp.c
> > index 7557ab551295..53e0fb0562c1 100644
> > --- a/drivers/irqchip/irq-armada-370-xp.c
> > +++ b/drivers/irqchip/irq-armada-370-xp.c
> > @@ -359,16 +359,16 @@ static void armada_370_xp_ipi_send_mask(struct irq_data *d,
> >  		ARMADA_370_XP_SW_TRIG_INT_OFFS);
> >  }
> >
> > -static void armada_370_xp_ipi_eoi(struct irq_data *d)
> > +static void armada_370_xp_ipi_ack(struct irq_data *d)
> >  {
> >  	writel(~BIT(d->hwirq), per_cpu_int_base + ARMADA_370_XP_IN_DRBEL_CAUSE_OFFS);
> >  }
> >
> >  static struct irq_chip ipi_irqchip = {
> >  	.name		= "IPI",
> > +	.irq_ack	= armada_370_xp_ipi_ack,
> >  	.irq_mask	= armada_370_xp_ipi_mask,
> >  	.irq_unmask	= armada_370_xp_ipi_unmask,
> > -	.irq_eoi	= armada_370_xp_ipi_eoi,
> >  	.ipi_send_mask	= armada_370_xp_ipi_send_mask,
> >  };
> 
> This fixes it, yes \o/

Thanks. Can I use this as a Tested-by: tag in the official patch?

	M.

-- 
Without deviation from the norm, progress is not possible.

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